On vector-valued modular forms and their Fourier coefficients Marvin Knopp; Geoffrey Mason — 2003 Acta Arithmetica
On Dirchlet's series satisfying Riemann's functional equation. Marvin I. Knopp — 1994 Inventiones mathematicae
On Dirichlet series and Hecke triangle groups of infinite volume Marvin I. Knopp; Mark Sheingorn — 1996 Acta Arithmetica